Flash-light lamp



Jan. 29 1935.

FLASH LIGHT LAMP Filed April 20; 1932 F "for; 7 jay- YQ" 'le r fe dens A J J 2.3 an.

J. M. VAN LIEMPT El A l 1,989,572

Patented Jan. 29, 1935 FLASH-LIGHT LAMr Johannes Antonius Maria Van Liempt and Pieter Leydens, Eindhoven, Netherlands, assignors to N. V. Philips Gloeilampenfabrieken, Eindhoven,

Netherlands Application April 120, 1932, Serial No. 606,444 In the Netherlands July 2, 1931 12 Claims.

Flash-light lamps are known in which the reactive material is contained in a transparent hollow body which is entirely or partly exhausted. Such a flash-light lamp may be constructed in such manner that a metal body which, when heated directly or indirectly, enters into a reaction with a gas filling, such a body being provided in a glass bulb having the shape of an electric incandescent lamp and containing a gas filling consisting, for example of oxygen or an oxygen compound or again of a mixture of oxygen and hydrogen. It has also been proposed to furnish a flash-light lamp constructed in the shape of an electric incandescent lamp, with a flash-light powder which can be electrically ignited. Furthermore, in our copending patent application Ser. No. 594,910, filed February 24, 1932 there is described a flash-light lamp provided with a gas filling in which by electrical ignition a gas reaction may be brought about, the actinic efiect of the flash-light lamp being substantially obtained by this gas reaction. As is well known, the ignition of such a lamp gives rise to the'production of a considerable amount of heat, owing to which the pressure in the bulb increases. The danger of destruction of the wall of the bulb may often be avoided by giving the latter suitable dimensions and by taking suitable quantities of the reactive material to be introduced into the bulb. Thus, for example, a quantity of aluminium may be adapted to'the quantity of oxygen so that after the combustion all the oxygen is consumed. It may happen, however, that these measures do not afford sufiicient safety if for some reason or other for example, due to a crack produced in the bulb the latter becomes leaky so that, owing to the fact that the pressure in the bulb is .below atmospheric, air is drawn into the latter. In fact, due to the heat produced by the explosion the air contained in the bulb will be heated and the pressure will greatly increase so that the risk of the bulb being destroyed considerably increases.

The object of the invention is to prevent the persons handling or in the vicinity from being exposed to such a danger.

The invention consists of a flash-light lamp with electrical ignition in which the material which is to be brought to reaction with actinic efiect, is contained in a transparent hollow body which is entirely or partly exhausted and which contains a substance whereby any penetration of air into the hollow body is made visible. As a substance suitable for carrying out the invention may be mentioned, for example nitric oxide (NO),.wh ich when exposed to air forms a mixture of N204 and N02. The N204 gives a reddish brown color and advantage is taken of this coloration to detect leaky lamps. Thus if a flash-light lamp containing nitric oxide (NO) has taken up some air, the user is consequently warned by the coloration that with this lamp there exists the danger that due to the explosion of the reactive substances the bulb may burst into pieces.

One form of our invention is shown in the accompanying drawing, which is an elevation of a lamp embodying our invention.

According to this drawing the bulb 1 is provided with a gas mixture of carbon disulfide and nitric oxide. A pinch 21 is provided in the .with such a flash-light lamp the danger of the bulb being destroyed is very small. It use is made of the glass bulbs usually employed for electric incandescent lamps, this danger may be reduced still more by giving the pressure of the gas mixture a value lower than about cms. of mercury. This seems to be due. to the fact that when air penetrates into a leaky bulb the oxygen of air combines with the nitric oxide (N0) of the reaction gas mixture and forms N204 and nitrogen peroxide (N02) while the nitrogen of the air acts as a so-called damper.

A particular advantage of the last-mentioned form of execution consists in that the temperature of ignition of the reaction gas mixture consisting of carbon disulfide and nitric oxide (NO) is so high that in the manufacture of a flashlight lamp-having the shape of an electric incandescent lamp, the exhaust tube can be closed without requiring special measures.

On examining the 'actinic effect of gas mixtures of carbon disulfide and nitric oxide (N0) of different compositions it has been found that in the region of pressure ranging from 10 to 'Moms. of mercury a maximum actinic efiect is obtained by the explosion of gas mixtures composed of 1 vol. CS2 to 1.5 vol.'NO up to 1 vol. CS2 to 3.5 vol. NO, depending on the pressure. Particularly favourable are those mixtures of carbon disulfide and nitric oxide (NO) which'are composed of between 1 vol. CS2 to 2.25 vol. NO, and 1 vol. CS2 to 2.75 vol. NO.

When use is made of an incandescent body for bringing a cut the ignition in the gas mixture of carbo disulfide and nitric oxide (NO) it is necessary that the incandescent body should rapidly reach the temperature required for the ignition. In fact, if the period of time for reaching the proper ignition temperature is too long, the danger exists that the incandescent body which is already hot is chemically attacked and is destroyed before it has reached the temperature required for the ignition of the said reaction gas mixture. This must be taken into account when determining the dimensions of the incandescent body, which consequently must have a rather high melting point. Thus, use may conveniently be made of an incandescent body of molybdenum or tungsten which may be platinized in order to obtain on the body a chemically highly resistant layer.

It is evident that in a flash-light lamp which contains a gas filling consisting entirely or partly of oxygen and in which for example, magnesium or aluminium is brought to a rapid combustion, it is impossible to utilize a substance such as nitric oxide (NO) for making the access of air visible. In this case the oxygen may be replaced, for example, by nitrous oxide, and the gas filling-may consist of a mixture of, say, N20 and 10% NO. The gas filling may also entirely consist of nitric oxide (NO).

Another mode of realization of the invention consists in introducing into the bulb the white substance produced asa precipitate by bringing together a boiled-out solution of ferrous sulfate and a boiled-out solution of potassium ferrocyanide. If air should penetrate into the bulb this white precipitate assumes at once a blue colour. Said precipitate may be introduced into the bulb in the following manner.

Two capillary tubes 7, 7 of which one is filled with a boiled-out solution of ferrous sulfate and the other with a boiled-out solution of potassium ferrocyanide may be used. After the air has been withdrawn from the bulb by means of a pump, the capillary tubes are destroyed by shaking them for which purpose it is advisable to provide said tubes beforehand with a scratch 8. Thus, a white precipitate is produced on a small portion of the wall of the bulb whereupon the pumping operation is continued and then the bulb is fused off.

The nature of the light may be influenced by applying to the filament 4, for example, a sodium compound and a strontium compound to which are preferably added a barium salt and a calcium salt, as shown at 9, or again by adding a small amount of an inert gas such as helium owing to which the intensity in the yellow and red portions of the actinic light is enhanced. This influencing of the nature of the light is particularly important when use is made of the above-described gas mixture of nitric oxide (NO) and carbon disulfide in connection with the nature of the actinic light thus obtained.

Use may conveniently be made of an igniting .mass owing to which the duration of the luminous efi'ect may be reduced. As an example of a suitable igniting mass may be mentioned a mixture consisting of a substance evolving oxygen such as barium nitrate or potassium chlorate with finely divided metal powder such as aluminium or iron while, for example dextrin may be used as a binder. Such a mixture would be applied to the filament in the relative position of the salt 9, and perhaps might be mixed therewith.

What we 'claim is:--

1. A flashlight lamp comprising a sealed and at least partly exhausted transparent envelope, electric ignition means, and a material which indicates by coloration the presence of air which has penetrated into said envelope, and adapted to be brought by said ignition means to a reaction temperature with actinic efiect.

2. A flashlight lamp comprising a sealed transparent envelope, electric ignition means, and a material which is adapted to be brought. by said ignition means to a reaction with actinic effect, said material comprising nitrogen monoxide.

3. A flashlight lamp comprising a transparent envelope, electric ignition means, and a gas filling consisting of a reaction gas mixture of carbon disulphide and nitrogen monoxide, said nitrogen monoxide indicating by coloring, the presence of air penetrated into said envelope.

4. A flashlight lamp comprising a sealed and at least partly exhausted transparent envelope, electric ignition means, and a gas filling which by said ignition means is brought to a gas reaction with actinic eflect, said gas filling comprising carbon disulphide and nitrogen monoxide between the limits of one volume carbon disulphide to 1.5-3.5 volumes of nitrogen monoxide.

5. A flashlight lamp comprising a sealed transparent envelope, electric ignition means, and a gas filling which is brought to a reaction with actinic effect by said ignition means, said gas filling consisting of one volume carbon disulphide and 2.25 to 2.75 volumes nitrogen monoxide.

6. A flashlight lamp comprising a transparent envelope, electric ignition means, and a material which is brought to a reaction with actinic effect by said iginition means, said material comprising a substance which indicates by coloring, the presence of air penetrated into said envelope, and means to increase the yellow and red portions of the actinic light emitted by the lamp.

7. A flashlight lamp comprising a transparent envelope, electric ignition means and a gas filling consisting of carbon disulphide and nitrogen monoxide, and means to increase the actinic efiect in the yellow and red portions of the spectrum.

8. A flashlight lamp comprising a transparent envelope, electric ignition means, and a gas filling which is brought by said ignition means to a reaction with actinic effect, and a sodium compound in said lamp to increase the actinic effect in the yellow portion of the spectrum.

9. A flashlight lamp comprising a sealed transparent envelope, electric ignition means, and a gas fllling'which is brought to a gas reaction with actinic effect by said ignition means, and a strontium compound in said lamp to enhance the actinic efiect in the red portions of the spectrum.

10. A flashlight lamp comprising a sealed transparent envelope, electric ignition means, and a gas filling comprising a reaction gas mixture of carbon disulphide and nitrogen monoxide, said gas filling being adapted to be brought to a reaction with actinic effect by said ignition means, and a barium salt within said envelope.

11. A flashlight lamp comprising a sealed transparent envelope, electric ignition means and a gas filling comprising a reaction gas mixture of carbon disulphide and nitrogen monoxide, adapted to bebrought to a reaction with actinic effect by said ignition means, and a calcium salt within said envelope.

12. A flashlight lamp comprising a sealed and at least partly exhausted transparent'envelope, electric ignition means, and a material within said envelope adapted to be brought by said ignition means to a reaction with actinic efiect, and a substance in said envelope, said substance indicating by coloration the presence of air in the envelope.

JOHANNES ANTONIUS MARIA VAN LIEMPT.

PIETER LEYDENS'. 

